Environmentally friendly cars (also known as green cars or eco-friendly cars), including both hybrid vehicles (HEVs) and electric vehicles (EVs), are well known. Typically, the HEV uses two or more distinct types of power, such as an internal combustion engine and an electric motor, while the EV is propelled by one or more electric motors, using electrical energy stored in rechargeable batteries or other energy storage device. While operating, the HEV can use a generator to make a battery self-powered so that the battery can supply power for vehicle operation. The HEV can include a regenerative braking system which converts its kinetic energy occurred by a counter-rotating motor during braking of the vehicle into an electric form either used immediately or stored in batteries for later use in order to increase energy efficiency.
Like many electronic devices, the EV is designed to operate after being charged. Charging equipment for charging a battery equipped in the EV can be implemented in various types or structures. For example, one type of charging equipment is an On-Board Charger (OBC) equipped in the EV for converting an Alternating Current (AC) power into a Direct Current (DC) power to charge the battery. Since it is installed in the EV, the OBC should be controllable via internal communications with other devices or equipment included in the EV. Further, an operational liability of the OBC as one of vehicle parts is required, and downsizing or lightening of the OBC can be a critical issue for its design.
For designing a charging device configured to charge the EV, there might be some important issues such that an overall capacity of a battery or batteries included in the EV continues to increase, and reducing a charging time is required for vehicle mobility even though the capacity of batteries is increased. However, so as to reduce a charging time for plural batteries equipped in the EV, a lot of cost and time can be spent on designing and installing plural different chargers, each corresponding to different charging capabilities. Further, in order to correspond with different charging capabilities of plural batteries included in the EV, a charging device equipped in the EV can be required to have an additional device for power conversion.
To overcome above-described issues, an apparatus or a method for charging plural chargeable units, each coupled in parallel, equipped in the EV can be applicable. However, there is difficulty in controlling the plural chargeable units en bloc because the plural chargeable unit can operates individually.